This invention relates to gas turbine engines, and more particularly, to a pulse detonation system for a turbofan engine.
Variable cycle turbofan ramjet engines may be used to provide aircraft flight speeds between low subsonic Mach numbers to high supersonic Mach numbers of about Mach 6. Known engines, as described in U.S. Pat. No. 5,694,768, include a core engine system and a dual mode augmentor. The dual mode augmentor provides additional heat to exhaust airflow exiting the core engine system to increase engine thrust. The core engine system provides power to drive a fan assembly and typically includes in serial, axial flow relationship, a compressor, a combustor, a high pressure turbine, and a low pressure turbine. The dual mode augmentor is positioned downstream from the core engine and receives air from the core engine and a bypass duct surrounding the core engine.
Known engines can operate over a wide range of flight speed operations if several different combustion systems are utilized. During flight speed operations from takeoff to approximately Mach 3, the core engine and an engine fan system provide airflow at a pressure and quantity used by the augmentor to produce thrust for the engine. To maintain flight speed operations between Mach 3 and Mach 6, the core engine system is shut-down and ram air flow is introduced into the dual mode augmentor either by windmilling the fan system or by utilizing an auxiliary ram duct. To sustain flight speed operations above Mach 6, either a separate supersonic combustion system, i.e., a scramjet, is used, or a separate rocket-based thrust producing system is used. To achieve flight speed operations in space, the rocket-based thrust producing system is used. As a result, for an engine to operate efficiently over a wide range of operating flight speeds, several different combustion systems are used.
In an exemplary embodiment, a pulse detonation system for a turbofan engine is disclosed. The turbofan engine includes a fan assembly and a turbine sub-system. The turbine sub-system includes at least one turbine. The pulse detonation system is configured to create a temperature rise and a pressure rise within the turbofan engine and to generate thrust for the turbofan engine. The pulse detonation system includes a pulse detonation core replacement assembly comprising at least one detonation chamber configured to detonate a fuel mixture. The pulse detonation core replacement assembly is positioned between the fan assembly and the turbine sub-system.
A turbofan engine embodiment is also disclosed. The turbofan engine includes a fan assembly, at least one turbine downstream from the fan assembly, an inlet portion upstream from the fan assembly, an exhaust portion positioned co-axially with the inlet portion, and a pulse detonation system positioned between the fan assembly and the turbine. The pulse detonation system is configured to create a temperature rise and a pressure rise to generate engine thrust for the turbofan engine. The pulse detonation system includes a pulse detonation core assembly comprising at least one detonation chamber configured to detonate a fuel mixture. The pulse detonation core assembly is positioned between the fan assembly and the turbine.